Why Does a Ruler Rise Up a Pencil When Swung at Higher Frequencies?

[Lil_Aziz1]

Hey everyone. So I was bored and I started swinging my ruler around my pencil (my ruler has a little hole where my pencil can be inserted into). Then I remembered we talked about why the ruler starts to go up the pencil if frequency increases in my physics class last year. The thing is, I can't remember why exactly this happens. I just remember talking about it. Now when frequency goes up, angular velocity goes up, then angular acceleration goes up, and then centripetal acceleration goes up. What's providing the centripetal acceleration? The normal force from the pencil (I think). However, this does not answer how it goes up the pencil because centripetal acceleration is horizontal and force of gravity is downward.

Can anyone help me out?

Thanks in advance!

 

[K^2]

Erm. I'm having hard time picturing exactly what you are doing and what do you mean by going up. Do you mean swinging it in a vertical or horizontal plane?

 

[skeptic2]

Could it be that as you are twirling the ruler your pencil is tracing out a cone? As the speed increases, the inertia of the pencil creates more force force the ruler to move outward and upward on the pencil than gravity creates to move it downward.

 

[pallidin]

Could it be that as you are twirling the ruler your pencil is tracing out a cone? As the speed increases, the inertia of the pencil creates more force force the ruler to move outward and upward on the pencil than gravity creates to move it downward.

Exactly.

 

[PJC01]

Hello! It's great that you're exploring the physics behind swinging a ruler around a pen. The phenomenon you observed is known as centripetal force, which is the force that keeps an object moving in a circular path. In this case, the centripetal force is provided by the tension in the string or hole of the ruler, which pulls it towards the center of the circle.

As you correctly stated, when the frequency of the ruler's motion increases, so does its angular velocity, angular acceleration, and centripetal acceleration. This means that the ruler is moving faster and its path becomes more curved, requiring a greater force to keep it in that circular motion.

You also mentioned the normal force from the pencil as a possible source of centripetal acceleration. While the normal force does play a role in keeping the ruler from falling down, it is not the main source of the centripetal force. Instead, it is the tension in the string or hole of the ruler that provides the necessary force to keep the ruler moving in a circular path.

I hope this helps clear up any confusion and that you continue to explore and learn more about the principles of physics. Keep up the curiosity and experimentation!